To obtain quantitative information on the inhibitory effects of antitumor drugs on the following hematopoietic cell compartments: 1) primitive stem cells, 2) intermediate stem cells, and 3) differentiated-dividing cells. To test compounds (erythropoietin, endotoxin, leukocytosis-promoting urine concentrates) for their effects on the regeneration of hematopoietic tissue after its suppression by antitumor drugs, and to obtain from such experiments, information on cytokinetics and regulation of hematopoietic precursors.